The present invention relates to a plasma processing apparatus and in particular relates to a plasma processing apparatus suitable for use in a plasma etching in the manufacture of a semiconductor device etc., and an apparatus in which a thin film is generated by using a plasma such as a plasma CVD (Chemical Vapor Deposition) etc.
As a conventional plasma processing apparatus, a technique is disclosed in Japanese patent laid-open publication No. Hei 8-102,279. This publication describes a small-sized permanent magnet and a homogeneous plasma extending to a wide range in a plasma generating chamber and also a high density plasma. The conventional plasma processing apparatus comprises a waveguide portion for introducing microwave energy, an electron heating space chamber portion formed in a position of a downstream side of a dielectric body in the waveguide portion, and a plasma generating chamber connected to the electron heating space chamber portion. A first magnetic field generating means surrounds an outer periphery of the electron heating space chamber portion, forms a strong magnetic field which exceeds an electron cyclotron resonance magnetic field strength in a microwave lead-through portion of the dielectric body along a transmission direction of the microwave energy, and forms a cup-shaped magnetic field in which a direction is reversed against the magnetic field following a direction of a plasma generating chamber from a boundary portion between the electron heating space chamber portion and the plasma generating chamber, whereby a magnetic field abruptly decreases at the boundary portion between the electron heating space chamber portion and the plasma generating chamber from the microwave lead-through portion of the dielectric body. A second magnetic field generating means comprises permanent magnets which are arranged by alternating the order of their polarities at a surrounding portion of the plasma generating chamber.
However, since the electron heating space chamber portion is formed in the waveguide portion, in a case where a pressure in an enclosed vessel (the plasma generating chamber) becomes more than 1 mTorr, the diffusion of the electrons from the electron heating space portion is difficult. Therefore, there is a problem that it is impossible to make the plasma density of the plasma generating chamber large.